Body boards for riding waves and other recreational sports boards made of foam or other floatational material are known in the prior art. In general, such boards are composed of a number of polyethylene foam and polyethylene film layers that are laminated together by heating the layers and then immediately passing them through a pair of nip rollers. Another conventional process of lamination is to apply heat to the film layer with a heated nip roller on the film side and a normal nip roller on the foam side, where the heated nip roller may be a flat roller. In most cases the surface of the heated nip roller contains an engraved pattern of convex and concave area for better heat transfer. Both of these conventional heating processes cause adhesion by the localized collapse and bonding of the foam cells on the surface of the respective layers. The resulting laminate of the polyethylene foam and polyethylene film is then often heat laminated onto a standard foam core.
Because the standard foam core does not have a perfectly flat or planar surface, adhesive contact between the film and foam core is limited to the apexes of the cells on the surface of the foam core. Thus the point of contact is not uniform between the film and foam, but instead the film contacts the points of the outer surface of the core that protrude from the irregular cellular surface of the foam core.
Conventional film lamination method typically use micro-cellular high density foam sheets to improve the adhesion between the film and foam core. The micro-cellular foam sheet contains smaller peaks and valleys, with the peaks closer together. The surface area of contact between the sheet and foam is thereby increased. However, this kind of structure is still prone to delamination by mechanical contact forces and by the effect of heat and pressure when in use.
While it is known in the prior art that a thin layer of thermal plastic polyethylene film between a polyethylene foam sheet and a polyethylene film can be used to promote lamination, such thin layer of film is generally an unmodified low density polyethylene with limited efficacy.
Accordingly, there is need for adhesively bonded sports boards with improved bonding between layers of different polymeric material having different surface contouring and cellular structure.